How many finished pieces fit on a parent sheet, how they sit on it, and how much of the sheet ends up as trim. Change any number and the layout redraws.
The arithmetic, in full
Nothing here is hidden, so you can check it against a sheet you have already run:
- Usable sheet = parent − twice the edge margin. The margin is the gripper and tail your press cannot image.
- Across and down are whole pieces only — the remainder is waste, not a partial piece.
- Both orientations are tried and the better one wins. The losing one is still shown, because sometimes you want the grain the other way even at a lower count.
- Waste = 1 − (pieces × finished area) / sheet area. It counts trim, gutter and margin together, which is the number that matters when you are costing paper.
Shared cut line, or every piece trimmed
This is the setting that changes the answer most, and the one most calculators get wrong by ignoring it.
With a shared cut line, neighbouring pieces are trimmed together: one cut serves both, so bleed only appears around the outside of the block. This is how gang runs are normally imposed.
With every piece trimmed, each one carries bleed on all four sides — the case for die-cut work, or anything cut individually.
The gap is not academic. A 50 × 50 mm piece on SRA3 with 3 mm bleed and a 3 mm margin fits 48 up on a shared cut line and 35 up trimmed individually — a 37% difference in how much paper you buy.
Why the margin matters more than people expect
Edge margin comes off both sides of both dimensions, so a few millimetres can cost you a whole column. A6 postcards on SRA3 fit 8 up at a 3 mm margin and drop to 4 up at 10 mm — the pieces did not change, the usable sheet did. If your press can hold a tighter gripper than you have assumed, that is often the cheapest yield you will find.
What this does not do
It is a sheet-fitting calculator, not an imposition RIP. It does not step-and-repeat a file, handle work-and-turn or work-and-tumble, impose multi-page signatures, or account for creep on a folded section. For a flat job — cards, postcards, flyers, labels — it tells you the number you need before you quote.